1. Field of the Invention
The present invention relates to a tire vulcanizing press.
2. Description of the Prior Art
Referring to a prior art tire vulcanizing press according to FIG. 2, reference numeral (01) denotes one press body (side plate) of a pair, and (02) a base. Each press body (01) is fixed on a respective one of opposite sides of the base (02). Reference numeral (03) denotes a vertical roller guide groove provided on a front top portion of each press body (01), (04) a nearly horizontal roller guide way provided on a rear top portion of each press body (01), (05) a beam (upper die support structure), (06) a beam shaft projecting outward of opposite end portions of the beam (05), and (07) one of a pair of guide rollers (beam rollers) which are supported rotatably on each beam shaft (06) at ends thereof. Each guide roller (07) is rollably supported in the vertical roller guide groove (03) of each press body (01). Reference numeral (08) denotes a crank gear, and character (A) denotes a center of rotation of the crank gear (08), the center of rotation (A) and a vertical center line of the vertical roller guide groove (03) lying in the same vertical plane. Further, (09) denotes a motor operatively connected to a reduction device, (010) a pinion driven by the motor (09), the pinion (010) engaging the crank gear (08). Reference numeral (011) denotes a crank pin mounted on the crank gear (08) at an eccentric position, and (012) a crank arm (side link). A lower end portion of the crank arm (012) is mounted rotatably on the crank gear (08) through the crank pin (011), and an upper end portion of the crank arm (012) is mounted rotatably on the beam shaft (06). Further, reference numeral (013) denotes an upper can supported on the beam (05), and an upper die and an upper pressure plate are incorporated in the upper can (013). Reference numeral (014) denotes a lower can supported on the base (02), and a lower die and a lower pressure plate are incorporated in the lower can (014). When the motor (09) coupled with the reduction device is driven, such rotation is transferred to the crank gear (08) through the pinion (010). The crank gear (08) is thus rotated around the center of rotation (A) in the direction indicated by an arrow X, the crank pin (011) is shifted from a bottom dead point (B.sub.1) to a last point (B.sub.5) by way of an intermediate point (B.sub.2).fwdarw.an intermediate point (B.sub.3) and.fwdarw.a top dead point (B.sub.4). The crank arm (012) is thus cranked, and when the crank pin (011) shifts from the bottom dead point (B.sub.1) to the intermediate point (B.sub.2), the guide roller (07) is elevated along the vertical roller guide groove (03) ((C.sub.1).fwdarw.(C.sub.2)), the beam shaft (06) and the beam (05) and the upper can (013) are elevated vertically, and the upper can (013) is isolated from the lower can (014) by an interval (l). Then, when the crank pin (011) shifts.fwdarw.the intermediate point (B.sub.3).fwdarw.the top dead point (B.sub.4) and.fwdarw.the last point (B.sub.5), the beam roller (07) is brought out of the vertical roller guide groove (03) to roll on the nearly horizontal roller guide way (04) ((C.sub.3).fwdarw.(C.sub.4).fwdarw.(C.sub.5)), the beam shaft (06) and the beam (05) and the upper can (013) are shifted rearward to facilitate the removal of tires, the feeding of half-finished goods, and maintenance such as the replacement of dies and so forth. Then, when these operations are over, the crank gear (08) is rotated counted to the direction mentioned above, the upper can (013) is returned to a closed position, and a tire vulcanizing process is recommenced.
In the prior art tire vulcanizing press shown in FIG. 2, the interval (l) between the upper can (013) and the lower can (014) is not sufficient to facilitate the removal of tires, the feeding of half-finished goods, and maintenance such as the replacement of dies and so forth. Therefore, a satisfactory interval must be provided between the upper can (013) and the lower can (014) by moving the upper can (013) rearward along the nearly horizontal roller guide way (04). The upper can (013) is so moved during a normal operation of tire production and at the time maintenance such as die replacement or the like, which gives rise to the following problem. That is, since the guide roller (beam roller) (07) rolls on the nearly horizontal roller guide way (04) rearwards while bearing the full weight of the upper can (013), the guide roller (07) and the nearly horizontal roller guide way (04) are relatively worn out shortly, and particularly when the guide roller (07) is worn out, a gap between the beam roller (07) and the vertical roller guide groove (03) increases, a concentricity between the upper can (013) and the lower can (014) is not obtainable, and thus a precision of the produced tire deteriorates.